Hi
There are 3 types of RCD tripping units I know of. They are marked A,C or D after the currant rating of the RCD. I have found that the ones marked A or C are more prone to tripping on start up currants than the ones marked up with a D.
Might be worth checking.
Isolation Transformer = 2 matched coils on a common iron former insulated from each other, one coils magnetic field is induced into the other coil. i.e 240volts in 240volts out.
The earthing on mine is not decoupled from the mains earthing so I still need a galvanic isolator.
Removing the earth could be dangerous as if a nuetral fault occured on the boats wiring, the boat hull could become live and anybody touching the boat and an earthed walkway or even a swimmer touching the boat in certain surcumstances could get a shock.
There are some websites you can visit. Just type in- What is an Isolation Transformer ?
Regards
Stylus